The first-ever spacewalk by private civilians has been successfully attempted, with four passengers on board SpaceX’s Polaris Dawn mission being subjected to outer space conditions for about one hour.

The four-person crew will now start their journey back down to Earth on board the spacecraft, with a splashdown expected off the Gulf of Mexico on Saturday.

How did the spacewalk go?

The first-ever commercial spacewalk was delayed for about two and a half hours, with the spacewalk starting at about 10:50 GMT after the hatch of the spacecraft was opened.

Before heading out, the pressure inside the capsule was slowly altered as part of the “pre-breathing” process that prepares the astronauts’ bodies. When the hatch was opened, the spacecraft was travelling at an elliptical orbit of 736km (457 miles) above the surface of the Earth at a speed of more than 25,000km/h (at least 15,500mph).

As billionaire mission commander Jared Isaacman opened the hatch and stepped up to transmit the first view of the planet from outside, the SpaceX crew on Earth erupted into cheers. He began limb movements which he had memorised beforehand to test out mobility in outer space.

After a number of minutes with his body partially outside the hatch, the 41-year-old Isaacman withdrew and was replaced by SpaceX engineer Sarah Gillis, 30, who went through similar motions, turning side to side and flexing her limbs to see how the new spacesuit, designed to protect the crew from the harsh vacuum, would hold up.

US SpaceX engineer Sarah Gillis emerges via the hatch from the Dragon spacecraft, during the first private spacewalk performed by the crew of the SpaceX Polaris Dawn mission [Polaris Program/AFP]

They were the only ones to go through the hatch, secured by a 12-foot (3.6-metre) tether linked to the spacecraft. They used Skywalker, a hatch structure with hand-held mobility assistance hardware developed by the company, but neither fully exited the hatch.

The other two crew members, 50-year-old former United States Air Force commander Scott “Kidd” Poteet and 38-year-old SpaceX engineer and medical officer Anna Menon, stayed inside the Dragon capsule but were exposed to the vacuum and had their own mobility and transmission tasks to perform, along with supporting the other two members.

None of the crew experienced severe symptoms, which can include acute motion sickness that can prove fatal in extreme cases due to pressure differences.

The crew also conducted dozens of experiments, including inter-satellite laser communication between the spacecraft and Space X’s Starlink satellite constellation.

What is SpaceX hoping to achieve?

After spending more than two years preparing and training for the physical and mental strain of the challenge, the astronauts’ bodies were finally exposed to outer space conditions on Thursday.

The overarching goal of the Polaris programme is to develop and test technologies that will allow SpaceX to progress towards its long-term goal of achieving travel to and establishing extraterrestrial settlements on other plants, especially Mars.

A major goal of the risky spacewalk was to test the company’s new Extravehicular Activity (EVA) astronaut suits which were designed and developed specifically for this mission over two years.

SpaceX wants to improve the design of the suits to accommodate a larger variety of future astronauts of different body types and ages at lower costs as private space travel is set to expand.

The SpaceX suits do not include a Primary Life Support System (PLSS), a set of support equipment worn like a backpack by astronauts at the International Space Station (ISS) that allows them to float more freely through space and carry out more complex tasks outside the space station. The trimmed-down suit means that the crew received their life support (oxygen) via the long hoses that were attached to their spacecraft.

The company hopes to learn from the effects of conditions like high altitude and radiation exposure during the experimental mission.

The laser and satellite communications checks would allow for connectivity improvements in the future.

How significant is the Polaris Dawn mission?

The Polaris Dawn’s five-day trek into Earth’s Van Allen radiation belts, which began at about 1,000km (600 miles) above the Earth’s surface, kicked off at 09:23 GMT on Tuesday, after several weather delays had delayed the rocket’s takeoff by weeks.

The Falcon 9 rocket’s first-stage booster, which had detached from the spacecraft after its launch, successfully landed minutes after launch on Tuesday on a SpaceX platform named Just Read The Instructions positioned in the Atlantic Ocean.

The platform is a modified barge that has been outfitted with equipment to safely receive Falcon boosters at sea after high-velocity missions because they cannot carry enough fuel to land at the site they were launched from.

Polaris Dawn has already made history, as it reached a peak altitude of at least 1,400 kilometres (870 miles), surpassing the record set by NASA’s Gemini 11 mission in 1966 that reached 1,373km.

It has also been the farthest humans have travelled since the 1972 Apollo mission to the moon, and the farthest into space a woman has ever journeyed.

Isaacman, the CEO and founder of credit card processing company Shift4, bought Polaris Dawn – at an undeclared price – as one of three space trips from SpaceX founder Elon Musk in 2022. This was shortly after Isaacman’s return from his first private flight with the company that raised money for a leading paediatric cancer hospital in the US.

Who else is currently in space?

According to NASA, there are currently 19 people on missions in Earth’s orbit, which is humanity’s all-time record. They include seven staff members on board the ISS, a three-person crew of the Soyuz mission heading for a crew swap at the ISS, three astronauts on board China’s Tiangong space station and two test pilots of the Boeing Starliner flight to the ISS who are temporarily stranded there and will return to Earth in early 2025.

According to some experts, the mission violates an article of the Outer Space Treaty signed by world powers in 1967 during the Cold War. The article stipulates that the activities of non-government entities in outer space must be authorised and supervised by a state party. Polaris Dawn is not a NASA mission, and it is not regulated by the US government.